Petrology and tectonic significance of potassic feldspar augen granitoids in the Yukon-Tanana Terrane, Stewart River, Yukon Territory

Potassic feldspar-bearing auger granitoids are a fundamental component of the architecture of the Yukon-Tanana Terrane (YTT) and the Ancient Pacific margin of the northern Cordillera, forming a belt that extends from Alaska to southeast Yukon Territory. In the Stewart River and Dawson areas of the Yukon there are two suites of auger granites: a Late Devonian suite and a Permian suite not recognized elsewhere in the YTT. The Late Devonian (∼363 Ma) suite represents the first examples of arc magmatism along the western North American margin in the mid Paleozoic, whereas the Permian (∼260 Ma) suite represents a record of Permian arc built upon a preexisting Devonian arc system. This paper contains an integrated field mapping, geochemical, and Sm-Nd isotopic study of these two suites with the aim of understanding their petrology, geochemistry, basement and tectonic evolution of the YTT and ancient Pacific margin in the Late Paleozoic. (Abstract shortened by UMI.)...